Flier essential to meagre beginnings (5)
I believe the answer is:
grebe
'flier' is the definition.
(grebe is a kind of birdanimal)
'essential to meagre beginnings' is the wordplay.
'essential to' says the answer is hidden in the clue (I've seen this in other clues).
'GREBE' is hidden within 'meagre beginnings'.
(Other definitions for grebe that I've seen before include "Diving water bird" , "Diver" , "Duck-sized water-bird" , "Diving waterbird" , "Small diving waterfowl with a long neck" .)